The invention is based on an anti-skid braking apparatus having a multiple-circuit brake force amplifier and wheel brake cylinders supplied thereby, the apparatus further including anti-skid valves disposed between said brake force amplifier and said wheel brake cylinders, with the anti-skid valves arranged to be triggered via an electronic switching device. An anti-skid braking apparatus of this type is known (German Offenlegungsschrift No. 27 03 760).
In this known anti-slip braking apparatus, pressure is fed into the closed brake circuit in accordance with a predetermined piston position in the main brake cylinder, or in accordance with predetermined switch positions of switches disposed on the brake amplifier, which pick up the brake amplifier's various positions. Pressure medium is then fed from the reservoir of an energy supply apparatus into the closed brake circuit in response to appropriate signals, in order to generate braking pressure in that brake circuit.
It is true that such known designs are simple in structure; however, they are extraordinarily vulnerable to failure, because in the event of a failure it is the reservoir pressure and not the braking pressure which is effective in the brake circuit being supplied.